SEARCH · Searcharxiv

Results for “math.HO”

Search indexed arXiv papers on artificial intelligence, large language models, computer vision and robotics. Read source abstracts and follow links to arXiv.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources

arXiv2007

Ueber Eigenwerte, Integrale und pi^2/6: Die Idee der Spurformel (On eigenvalues, integrals and pi^2/6: The idea of the trace formula)

This is an expository article that results from a talk given to second year students at Oldenburg university. The aim of the talk was to show what beautiful and unexpected results may be obtained if one plays with daring analogies in a way that is usually not done in undergraduate education (unfortunately): We start from the fact that the sum of diagonal entries of a symmetric matrix equals the sum of its eigenvalues. We then guess an analogous formula where the matrix is replaced by a function of two real variables and sums are replaced by integrals in a systematic way. We show that this is indeed a worthwhile process: In a special case it yields that the sum of inverse squares of the positive integers is pi^2/6. Finally, an outline of the proof of the guessed formula is given, and further applications, for example to the connection between billiards and the frequencies of a drum, are explained.

math.HO↗

arXiv2008

Publier sous l'Occupation I. Autour du cas de Jacques Feldbau et de l'Académie des sciences

This is an article on mathematical publishing during the German occupation of France. Looking at the cases of four of them and especially at the case of Jacques Feldbau (one of the founders of the theory of fibre bundles), we investigate the way censorship struck the French mathematicians who declared jewish by the Statut des juifs of october 1940, and the strategies these mathematicians then developed. The way the Vichy laws have been discussed and applied at the Académie des sciences is investigated.

math.HO↗

arXiv2007

How close are the option pricing formulas of Bachelier and Black-Merton-Scholes?

We compare the option pricing formulas of Louis Bachelier and Black-Merton-Scholes and observe -- theoretically as well as for Bachelier's original data -- that the prices coincide very well. We illustrate Louis Bachelier's efforts to obtain applicable formulas for option pricing in pre-computer time. Furthermore we explain -- by simple methods from chaos expansion -- why Bachelier's model yields good short-time approximations of prices and volatilities.

q-fin.PR↗

arXiv2007

Poincaré's inequality and diffusive evolution equations

This paper addresses the question of change of decay rate from exponential to algebraic for diffusive evolution equations. We show how the behaviour of the spectrum of the Dirichlet Laplacian in the two cases yields the passage from exponential decay in bounded domains to algebraic decay or no decay at all in the case of unbounded domains. It is well known that such rates of decay exist: the purpose of this paper is to explain what makes the change in decay happen. We also discuss what kind of data is needed to obtain various decay rates.

math.AP↗

arXiv2007

Various analytic observations on combinations

E158 in the Enestrom index. Translation of the Latin original "Observationes analyticae variae de combinationibus" (1741). This paper introduces the problem of partitions, or partitio numerorum (the partition of integers). In the first part of the paper Euler looks at infinite symmetric functions. He defines three types of series: the first denoted with capital Latin letters are sums of powers, e.g. $A=a+b+c+...$, $B=a^2+b^2+c^3+...$, etc.; the second denoted with lower case Greek letters are the elementary symmetric functions; the third denoted with Germanic letters are sums of all combinations of $n$ symbols, e.g. $\mathfrak{A}=a+b+c+...$ is the series for $n=1$, $\mathfrak{B}=a^2+ab+b^2+ac+bc+c^2+...$ is the series for $n=2$, etc. Euler proves a lot of relations between these series. He defines some infinite products and proves some more relations between the products and these series. Then in §17 he looks at the particular case where $a=n,b=n^2,c=n^3$ etc. In §19 he says the Naudé has proposed studying the number of ways to break an integer into a certain number of parts. Euler proves his recurrence relations for the number of partitions into a $μ$ parts with repetition and without repetition. Finally at the end of the paper Euler states the pentagonal number theorem, but says he hasn't been able to prove it rigorously.

math.HO↗

arXiv2007

Wilson's theorem

We show that there are four possibilities for the product of all elements in the multiplicative group of a quotient of the ring of integers in a number field, and give precise conditions for each of the possibilities to occur. This generalisation of Wilson's theorem turns out to have been first discovered by M. Laššák (2000), but our proof is simpler and more direct.

math.NT↗

arXiv2007

On highly transcendental quantities which cannot be expressed by integral formulas

E565 in the Enestrom index. Translated from the Latin original, "De plurimis quantitatibus transcendentibus quas nullo modo per formulas integrales exprimere licet" (1775). Euler does not prove any results in this paper. It seems to me like he is trying to develop some general ideas about special functions. He gives some examples of numbers he claims but does not prove cannot be represented by definite integrals of algebraic functions. Euler has the idea that if we knew more about the function with the power series $\sum x^{t_n}$ where $t_n$ is the $n$th triangular number, this could lead to a proof of Fermat's theorem that every positive integer is the sum of three triangular numbers. This doesn't end of being fruitful for Euler, but in fact later Jacobi proves a lot of results like this with his theta functions. The last paragraph (§9) is not clear to me. My best reading is that there are infinitely many "levels" of transcendental numbers and that this is unexpected or remarkable.

math.HO↗

arXiv2007

The Structure of a Bernoulli Process Variation of the Fibonacci Sequence

We consider the structure of a variation of the Fibonacci sequence which is determined by a Bernoulli process. The associated structure of all Bernoulli variations of the Fibonacci sequence can be represented by a directed binary tree, which we denote X, with vertex labels representing the specific state of the recurrence variation. Since X is a binary tree, we can consider the term of a sequence variation given by a finite traversal of X represented by a binary code t. We then prove that the traversal of X that is the reflection of the digits of t gives exactly the integer term corresponding to t. We consider how to further this result with the statement of an additional conjecture. Finally, we give connections to Fibonacci expansions, the Stern-Brocot tree, and we apply our methods to the Three Hat Problem as seen in ``Puzzle Corner'' of the ``Technology Review'' magazine.

math.HO↗

arXiv2007

On the partition of numbers into parts of a given type and number

E394 in the Enestrom index. Translated from the Latin original, "De partitione numerorum in partes tam numero quam specie datas" (1768). Euler finds a lot of recurrence formulas for the number of partitions of $N$ into $n$ parts from some set like 1 to 6 (numbers on the sides of a die). He starts the paper talking about how many ways a number $N$ can be formed by throwing $n$ dice. There do not seem to be any new results or ideas here that weren't in "Observationes analyticae variae de combinationibus", E158 and "De partitione numerorum", E191. In this paper Euler just does a lot of special cases. My impression is that Euler is trying to make his theory of partitions more approachable,. Also, maybe for his own benefit he wants to say it all again in different words, to make it clear.

math.HO↗

arXiv2020

The Natural Philosophy of Kazuo Kondo

Kazuo Kondo (1911-2001) was Chair of the Department of Mathematical Engineering at the University of Tokyo, Japan. Over a period of 50 years, he and a few colleagues wrote and published a voluminous series of papers and monographs on the applications of analytical geometry within a diverse range of subjects in the natural sciences. Inspired by Otto Fischer's attempt at a quaternionic unified theory in the late 1950's he adopted the mathematics of the revered Akitsugu Kawaguchi to produce his own speculative unified theory. The theory appears to successfully apply Kawaguchi's mathematics to the full range of natural phenomena, from the structure of fundamental particles to the geometry of living beings. The theories are testable and falsifiable. Kondo and his theories are now almost completely unknown and this paper serves as the barest introduction to his work

math.HO↗

arXiv2008

A beginner's guide to forcing

This expository paper, aimed at the reader without much background in set theory or logic, gives an overview of Cohen's proof (via forcing) of the independence of the continuum hypothesis. It emphasizes the broad outlines and the intuitive motivation while omitting most of the proofs. The reader must of course consult standard textbooks for the missing details, but this article provides a map of the forest so that the beginner will not get lost while forging through the trees.

math.LO↗

arXiv2007

A Not-so-Characteristic Equation: the Art of Linear Algebra

Can the cross product be generalized? Why are the trace and determinant so important in matrix theory? What do all the coefficients of the characteristic polynomial represent? This paper describes a technique for `doodling' equations from linear algebra that offers elegant solutions to all these questions. The doodles, known as trace diagrams, are graphs labeled by matrices which have a correspondence to multilinear functions. This correspondence permits computations in linear algebra to be performed using diagrams. The result is an elegant theory from which standard constructions of linear algebra such as the determinant, the trace, the adjugate matrix, Cramer's rule, and the characteristic polynomial arise naturally. Using the diagrams, it is easy to see how little structure gives rise to these various results, as they all can be `traced' back to the definition of the determinant and inner product.

math.HO↗

arXiv2007

What is a superrigid subgroup?

This is an expository paper. It is well known that a linear transformation can be defined to have any desired action on a basis. From this fact, one can show that every group homomorphism from Z^k to R^d extends to a homomorphism from R^k to R^d, and we will see other examples of discrete subgroups H of connected groups G, such that the homomorphisms defined on $H$ can ("almost") be extended to homomorphisms defined on all of G. This is related to a very classical topic in geometry, the study of linkages.

math.HO↗

arXiv2007

A polynomial parametrization of torus knots

For every odd integer $N$ we give an explicit construction of a polynomial curve $\cC(t) = (x(t), y (t))$, where $°x = 3$, $°y = N + 1 + 2\pent N4$ that has exactly $N$ crossing points $\cC(t_i)= \cC(s_i)$ whose parameters satisfy $s_1 < ... < s_{N} < t_1 < ... < t_{N}$. Our proof makes use of the theory of Stieltjes series and Padé approximants. This allows us an explicit polynomial parametrization of the torus knot $K_{2,N}$.

math.HO↗

arXiv2007

Algebraic generality vs arithmetic generality in the controversy between C. Jordan and L. Kronecker (1874)

Throughout the whole year of 1874, C. Jordan and L. Kronecker were quarrelling over two theorems. On the one hand, Jordan had stated in 1870 a canonical form theorem for substitutions of linear groups; on the other hand, Karl Weierstrass had introduced in 1868 the elementary divisors of non singular pairs of bilinear forms (P,Q) in stating a key theorem of the theory of bilinear and quadratic forms. Although they would be considered equivalent as regard to modern mathematics, not only had these two theorems been stated independently and for different purposes, they had also been lying within the distinct frameworks of two theories until some connections came to light in 1872-1873, breeding the 1874 quarrel and hence revealing an opposition over two practices relating to distinctive cultural features. As we will be looking into the 1874 quarrel, our purpose will be to show how the complex identities of practices such as Jordan s canonical reduction and Kronecker s invariant computation highlight some cultural issues such as tacit knowledge and perceptions of history peculiar to individuals or communities as well as some local ways of thinking such as disciplinary ideals and internal philosophies of generality and simplicity.

math.HO↗

arXiv2007

Exponentiating $2\times2$ and $3\times3$ Matrices Done Right

We derive explicit formulas for calculating $e^A$, $\cosh{A}$, $\sinh{A}, \cos{A}$ and $\sin{A}$ for a given $2\times2$ matrix $A$. We also derive explicit formulas for $e^A$ for a given $3\times3$ matrix $A$. These formulas are expressed exclusively in terms of the characteristic roots of $A$ and involve neither the eigenvectors of $A$, nor the transition matrix associated with a particular canonical basis. We believe that our method has advantages (especially if applied by non-mathematicians or students) over the more conventional methods based on the choice of canonical bases. We support this point with several examples for solving first order linear systems of ordinary differential equations with constant coefficients.

math.HO↗

arXiv2007

Fermat's Four Squares Theorem

It is easy to find a right-angled triangle with integer sides whose area is 6. There is no such triangle with area 5, but there is one with rational sides (a `\emph{Pythagorean triangle}'). For historical reasons, integers such as 6 or 5 that are (the squarefree part of) the area of some Pythagorean triangle are called `\emph{congruent numbers}'. These numbers actually are interesting for the following reason: Notice the sequence $\frac14$, $6\frac14$, $12\frac14$. It is an arithmetic progression with common difference 6, consisting of squares $(\frac12)^2$, $(\frac52)^2$, $(\frac72)^2$ of rational numbers. Indeed the common difference of three rational squares in AP is a congruent number and every congruent number is the common difference of three rational squares in arithmetic progression. The triangle given by $9^{2}+40^{2}=41^{2}$ has area $180=5\cdot6^{2}$ and the numbers $x-5$, $x$ and $x+5$ all are rational squares if $x=11{97/144}$. Recall one obtains all Pythagorean triangles with relatively prime integer sides by taking $x=4uv$, $y=\pm(4u^{2}-v^{2})$, $z=4u^{2}+v^{2}$ where $u$ and $v$ are integers with $2u$ and $v$ relatively prime. Fermat proved that there is no AP of more than three squares of rationals.

math.NT↗

arXiv2007

Hyperbolic Geometry and Distance Functions on Discrete Groups

Chapter 1 is a short history of non-Euclidean geometry, which synthesises my readings of mostly secondary sources. Chapter 2 presents each of the main models of hyperbolic geometry, and describes the tesselation of the upper half-plane induced by the action of $PSL(2,\mathbb{Z})$. Chapter 3 gives background on symmetric spaces and word metrics. Chapter 4 then contains a careful proof of the following theorem of Lubotzky--Mozes--Raghunathan: the word metric on $PSL(2,\mathbb{Z})$ is not Lipschitz equivalent to the metric induced by its action on the associated symmetric space (the upper half-plane), but for $n \geq 3$, these two metrics on $PSL(n,\mathbb{Z})$ are Lipschitz equivalent.

math.GR↗